E-mail (“email”) has become an irreplaceable tool in today's business environment. Virtually all corporate employees rely on email in one way or another to communicate both externally with customers and internally with other employees. Email access may be provided by a user's Internet Service Provider (e.g., Pacific Bell, AT&T WorldNet™, America Online™, . . . etc), or by an Internet website (e.g., Yahoo™ Mail or Hotmail™). The average email consists of a message body, header, and, optionally, one or more attachments. The message body is created using an email application which provides a window for entering text. The header is used by the Internet service to direct the routing of the message and also to communicate certain user-specific information (e.g. access rights, authentication, etc.). The message body and header are small in size, typically on the order of 5 kilobytes (kb) or so, and require a low amount of network bandwidth utilization for transmission.
Email may also include one or more file attachments which are used for sending data stored on a user's computer or other electronic device. Attachments can include file types such as computer data, applications, graphics, text documents, and etc. Email attachments are appended to an outgoing email message so that the content of the one or more attachments can be distributed to one or more intended addressees. Email is a preferred method of distributing attachments that more than one person needs access to; however, the present invention is not so limited. Attachments may be appended to various other electronic messages including instant messages. Unlike the email message body and header, attachments are large in size, typically 500 kb and upwards. Attachments include files such as pictures, video clips, and audio streams, which require a large amount of bandwidth for transmission over a network.
In addition, a growing number of email users rely on portable, multi-purpose data processing devices such as Personal Digital Assistants (PDAs) which include both electronic messaging and personal information management (PIM) capabilities. As a result, portable data processing devices such as and programmable wireless telephones are becoming more powerful every day, providing users with a wide range of applications previously only available on personal computers. One limitation of current multi-purpose telephony and/or data processing devices such as PDAs is that they utilize a wireless network to communicate with a service provider. It is well-known that wireless networks have limited bandwidth which comes at a premium. Wireless service providers, for example, are required to pay per megabit for bandwidth utilization as well pay for data storage. As a result, there is a need for new methods to reduce bandwidth utilization and data storage requirements in wireless networks. In prior art wireless messaging systems; however, the message body, header and attachment(s) must be uploaded every time an email message is sent over the network. Thus, bandwidth must be used to send the attachment(s) every time an email message is sent whether or not the same attachment(s) is sent more than once. This creates a problem for wireless networks since wireless devices today have significant network bandwidth limitations.
A solution to reducing bandwidth utilization for sending and receiving email messages is to bypass uploading unnecessary attachments whenever possible since the attachment requires much more bandwidth than the message body and header. One way to accomplish this is to store a user's previously uploaded attachments at the wireless service. Thus, if previously uploaded attachments are stored at the service, they do not have to be uploaded again whenever another message containing the same attachment is subsequently sent across the network.